The present invention relates to a midsole structure for an athletic shoe or a sports shoe, and more particularly, to an improvement in a wavy, corrugated plate structure having a wavy, corrugated plate disposed at a midsole formed of a soft elastic material.
Japanese patent application publication No. 11-203 describes a midsole structure having a wavy, corrugated plate in use for various sports shoes. Such a midsole structure is composed of an upper midsole formed of a soft elastic material, a lower midsole disposed under the upper midsole and formed of a soft elastic material, and a wavy, corrugated plate interposed therebetween.
In such a structure, the upper and lower midsole secures cushioning properties on landing and the wavy, corrugated plate prevents lateral deformation of the midsole after landing, thereby achieving running stability.
On the other hand, there exists a need to prevent lateral deformation of the midsole more securely to achieve advanced running stability in sports such as tennis, basket ball, or the like where hard lateral movements are required. Such being the case, as shown in Japanese patent application publication No. 2001-8704, there is provided a wavy, corrugated plate with sidewalls extending upwardly and downwardly on opposite side edges thereof and disposed on opposite side surfaces of the midsole.
In this structure, when the upper and lower midsole is going to deform in a lateral direction after landing, the sidewalls of the wavy, corrugated plate restrain deformation of the upper and lower midsoles.
However, since such a wavy, corrugated plate with sidewalls is formed of a wavy board and a pair of side walls formed integrally with opposite side edges of the wavy board, a layout of molds for forming a wavy, corrugated plate becomes complicated, thus making a manufacturing cost higher.
The present invention has been made in view of these circumstances and its object is to reduce manufacturing cost of a wavy, corrugated plate structure with sidewalls in use for a sports shoe.